Dietary xylooligosaccharides modulate oxidative stress and pathogen resistance in growing rabbits

Abstract

Background: Given the high incidence of gastrointestinal disorders in intensive rabbit production, we assessed the effects of graded levels of xylooligosaccharides (XOS) on growth performance, nutrient digestibility and intestinal health in growing rabbits.

Methods: The 35-day-old weaned rabbits (889.41 ± 0.41 g) were randomly assigned to five dietary treatments (0, 0.2, 0.3, 0.4 or 0.5 g/kg XOS) and the trial lasted for 35 d.

Results: The results revealed that linear trend responses of body weight (BW) to XOS on d 21 and 35 (P ≤ 0.05). During d 1-21, 0.2 g/kg XOS increased average daily feed intake (ADFI) while 0.5 g/kg improved feed conversion ratio (FCR) significantly (P ≤ 0.05). Weight gain rate (WGR) showed a linear trend, while FCR showed a quadratic response (P ≤ 0.05). Throughout the 35-d trial, 0.2 and 0.3 g/kg XOS enhanced ADFI, and 0.4 g/kg XOS improved FCR significantly, average daily gain (ADG) demonstrated linear dose-responsiveness, while WGR and FCR showed quadratic trends (P ≤ 0.05). Notably, 0.2 g/kg XOS elevated serum glutathione peroxidase (GSH-Px) activity and ileal secretory immunoglobulin A (sIgA) levels. Furthermore, 0.3, 0.4 and 0.5 g/kg XOS reduced jejunal malonaldehyde (MDA) content, 0.4 g/kg XOS decreased serum MDA, and 0.5 g/kg XOS elevated serum immunoglobulin M (IgM) significantly (P ≤ 0.05). 0.2, 0.4, 0.5 g/kg XOS improved the digestibility of crude fiber (CF), 0.2 and 0.4 g/kg XOS increased acid detergent fiber (ADF), and neutral detergent fiber (NDF) also increased among all treatments, although 0.5 g/kg XOS reduced cellulase activity significantly (P ≤ 0.05). Furthermore, graded levels of XOS significantly changed the relative abundance of specific bacteria, and 0.4 and 0.5 g/kg XOS enhanced the content of valeric acid significantly (P ≤ 0.05).

Conclusions: In conclusion, dietary supplementation of XOS serves as an effective nutritional strategy to optimize bacterial community in the cecum, improve fiber digestion and valeric acid production, while enhances resistance to intestinal pathogen infection and oxidative stress in rabbit production.

Keywords: Bacterial community; Fiber; Growing rabbit; Nutrient digestibility; Xylooligosaccharides.

Fig. 1

Effects of XOS on survival rate and growth performance in growing rabbits. A The survival rate of growing rabbits. B–D BW on d 0, d 21 and d 35 in growing rabbits. E–H ADG, WGR, ADFI and FCR on d 1–21 in growing rabbits. I–L ADG, WGR, ADFI and FCR on d 21–35 in growing rabbit. M–P. ADG, WGR, ADFI and FCR on d 1–35 in growing rabbits. BW, body weight; ADG, average daily gain; WGR, weight gain rate; ADFI, average daily feed intake; FCR, feed conversion ratio

Fig. 2

Effects of XOS on antioxidant indices in serum and jejunum of growing rabbits. A The activity of SOD in serum of growing rabbits. B The activity of GSH-Px in serum of growing rabbits. C The content of MDA in serum of growing rabbits. D The activity of SOD in jejunum of growing rabbits. E The activity of GSH-Px in jejunum of growing rabbits. F The content of MDA in jejunum of growing rabbits. SOD, superoxide dismutase; GSH-Px, glutathione peroxidase; MDA, malondialdehyde

Fig. 3

Effects of XOS on immune indices in serum and ileum of growing rabbits. A The content of IgA in serum of growing rabbits. B The content of IgG in serum of growing rabbits. C The content of IgM in serum of growing rabbits. D The content of sIgA in ileum of growing rabbits. E The content of IgM in ileum of growing rabbits. F The content of MUC2 in ileum of growing rabbits. IgA, immunoglobulin A; IgG, immunoglobulin G; IgM, immunoglobulin M; sIgA, secretory immunoglobulin A; MUC2, mucin 2

Fig. 4

Effects of XOS on apparent digestibility of nutrient in growing rabbits. A The apparent digestibility of GE in growing rabbits. B The apparent digestibility of DM in growing rabbits. C The apparent digestibility of CP in growing rabbits. D The apparent digestibility of EE in growing rabbits. E The apparent digestibility of CF in growing rabbits. F The apparent digestibility of NDF in growing rabbits. G The apparent digestibility of ADF in growing rabbits. H The apparent digestibility of ADL in growing rabbits. GE, gross energy; DM, dry matter; CP, crude protein; EE, ether extract; CF, crude fiber; NDF, neutral detergent fiber; ADF, acid detergent fiber; ADL, acidic detergent lignin

Fig. 5

Effects of XOS on the activity of digestive enzymes in growing rabbits. A The activity of amylase in the ileum of growing rabbits. B The activity of lipase in the ileum of growing rabbits. C The activity of trypsin in the jejunum of growing rabbits. D The activity of cellulase in the caecum of growing rabbits. E The activity of hemicellulose in the caecum of growing rabbits. F The activity of pectinase in the caecum of growing rabbits

Fig. 6

Effects of XOS on the composition and diversity of bacterial community in cecum of growing rabbits. A Bacterial community composition at the phylum level in the caecum of growing rabbits. B Bacterial community composition at the genus level in the caecum of growing rabbits. C ACE indices of α diversity in the caecum of growing rabbits. D Chao 1 indices of α diversity in the caecum of growing rabbits. E Shannon indices of α diversity in the caecum of growing rabbits. F Simpson indices of α diversity in the caecum of growing rabbits. G Comparison of β diversity between CON and T1 group. H Comparison of β diversity between CON and T2 group. I Comparison of β diversity between CON and T3 group. J Comparison of β diversity between CON and T4 group

Fig. 7

Comparison of differential genus and correlation analysis with physiological indicators. A Comparison of differential genus in cecum of growing rabbits. B Correlation analysis between bacteria and physiological indicators. *, ** indicate P ≤ 0.05, P ≤ 0.01, respectively. Spearman's correlation coefficients are donated with a color gradient. Physiological indicators were correlated with each bacterium by Mantel test. Edge width corresponds to the Mantel's r statistic for the corresponding distance correlations, and edge color denotes the statistical significance